Electrical switch with housing having internal ground contact



W. N. SCHINK April 25, 1967 ELECTRICAL SWITCH WITH HOUSING HAVINGINTERNAL GROUND CONTACT Filed Feb. 21, 1966 ZZJi/iz'am I2. Schz'rzle M Mw United States Patent Ofiice 3,316,364 Patented Apr. 25, 1967 3,316,364ELECTRICAL SWITCH WITH HOUSING HAVING INTERNAL GROUND CONTACT William N.Schiuk, Crystal Lake, 111., assiguor to Indak Manufacturing Corp.,Northbrook, 111., a corporation of Illinois Filed Feb. 21, 1966, Ser.No. 529,051 10 Claims. (Cl. 200-16) This invention relates to electricalswitches.

One object of the present invention is to provide an electrical switchin which at least one contact is grounded to the casing of the switch ina new and improved manner.

A further object is to provide such a new and improved switch in whichthe grounded contact is mounted on or formed integrally with a portionof the casing.

It is a further object to provide such a new and improved switch inwhich the grounded contact is mounted on or formed integrally with a tabor lug projecting inwardly from one wall of the casing, adjacent theother contacts of the switch and in front of the insulating support forthe other contacts.

Another object is to provide a new and improved switch of the foregoingcharacter in which the grounded contact may take the form of a contactrivet or the like, mounted on such tab, or a contact point or bossformed integrally with such tab.

A further object is to provide such a new and improved switch in whichthe grounding of one or more contacts is accomplished at extremely lowcost and in such a manner that the switch is easy to manufacture andreliable in operation.

Further objects and advantages of the present invention will appear fromthe following description, taken with the accompanying drawings, inwhich:

FIG. 1 is a fragmentary side elevational view of an electrical switch tobe described as an illustrative em- .bodiment of the present invention.

FIG. 2 is a fragmentary rear elevational view of the switch.

along the line S-5 in FIG. 2.

FIG. 6 is a fragmentary cross section similar to a portion of FIG. 5 butshowing the manner in which the casing tab is bent inwardly after thegrounded contact rivet has been mounted thereon.

FIG. 7 is a fragmentary cross section similar to FIG. 6 but showing amodified construction in which the contact rivet is replaced with acontact point or boss formed integrally with the casing tab.

FIG. 8 is a fragmentary elevational view, taken generally as indicatedby the line 8-8 in FIG. 7.

FIG. 9 is a view similar to FIG. 4 but showing a switch utilizing themodified grounded contact of FIGS. 7 and 8 As already indicated, FIG. 1illustrates an electrical switch 10 which is especially well adapted forautomotive service, for use on automobiles, trucks or the like, but willalso find many other applications. The illustrated switch 10 comprisesan electrically conductive casing 12 which preferably is made of metal.As shown, the casing 12 is formed from sheet metal into a rectangularshape, but the present invention is applicable to casings of variousshapes and constructions.

A contactor 14 is movably mounted within the casing connected to thebody of the automobile.

12, preferably on a movable carriage 16. As shown, the carriage 16 isslidable longitudinally along the inside of the casing 12. Theillustrated casing 12 has a front wall 18 and a pair of longitudinalside walls 20 and 22 which serve as guides for the carriage 16. Thecasing 12 has a pair of end walls 24 and 26 which retain the carriagewithin the casing.

Various means may be provided for operating the carriage 16. Forexample, the illustrated switch is provided with an operating lever 28which is swingable about a pivot 30, mounted on a bracket 32 projectingforwardly from the casing 12. The lever 28 has an arm 34 which projectsrearwardly into the casing 12 and is received in an opening 36 formed inthe carriage 16. An appropriate slot or opening is formed in the frontwall 18 of the easing 12 to receive the arm 34. 1

The contactor 14 is movable into engagement with a plurality of contactsor points. Four such contact points 41-44 are provided in theillustrated construction. At least one of the contact points is groundeddirectly to the casing 12. In the illustrated construction, the contact41 is thus grounded, in a manner to be described in detail presently.

The other contacts 42-44 are mounted on a supporting member 46 made ofinsulating material. The member 46 preferably takes the form of aninsulating board or plate which is secured to the casing 12 so as toform the rear wall thereoff A plurality of tabs 48 or other fasteningelements are formed on the casing 12 to retain the insulating plate 46.The illustrated tabs 48 extend through slots or notches 50 which areformed in the edge portions of the insulating plate 46. The tabs 48 arebent or clinched inwardly, behind the insulating plate 46, so that theplate will be securely fastened to the casing.

The contacts 42-44 preferably take the form of rivets which extendthrough suitable openings 51 in th insulating plate 46. Suitableterminals 52-54 may be secured to the rear ends of the rivets 42-44 andagainst the rear or outer side of the insulating plate 46.

Suitable spring means are provided to press the co-ntactor 14 rearwardlyagainst the contacts 41-44 and also against the insulating plate 46.Thus, one or more springs may be provided between the contactor 14 andthe carriage 16. In the illustrated construction, a coil spring 56 iscompressed between the contactor 14 and the carriage 16.

The illustrated contactor 14 is retained and guided on the carriage 16by means of guide tabs or lugs 58 which project from the contactortoward the front of the switch. The tabs 58 are slidably retained innotches or slots 60 which are formed in the carriage 16.

In addition to biasing the contactor 14 rearwardly against the contacts41-44, the spring 56 biases the carriage 16 against the front Wall 18 ofthe casing 12. It is preferred to provide detent elements on the frontwall 18, and also on the carriage 16, to locate and detain the carriagein its various operating positions. The detent elements on theillustrated carriage take the form of ridges or lugs 62 which projectforwardly therefrom. As to the front wall 18, the detent elements takethe form of alternate ridges 64 and grooves 66, adapted to receive theridges 62. When the carriage 16 is moved along the inside of the casing,the detent projections 62 ride over the ridges 64 and into the grooves66. Due to the biasing action of the spring 56, the detent projections62 are detained in the grooves 66.

As already indicated, the grounded contact 41 is mounted or formed on aportion of the casing 12. Thus, the contact 41 is grounded through thecasing. When mounted in an automobile or the like, the casing isnormally Thus, the

casing becomes a part of the grounded side of the elec trical system.

In the construction shown in FIGS. l-6, the contact 41 takes the form ofa contact rivet which is secured to a tab or flange 68 extendinginwardly from one wall 20 of the casing 12. An opening or hole 70 isformed in the tab 68 to receive the contact rivet 41. It will be seenthat the tab 68 is folded or bent inwardly from the casing, so as toextend adjacent the front or inner side of the insulating plate 46. Itis preferred to arrange the tab 68 so that the front or inner side ofthe insulating plate 46 firmly engages the rear side of the tab 68, sothat the contact rivet 41 will be in the same plane as the other contactrivets 42-44. The heads of the contact rivets 42-44 are made thickerthan the head of the rivet 41, so as to allow for the thickness of thetab 68.

In the construction of FIGS. 1-6, it is preferred to form an opening orhole 72 in the insulating plate 46, to receive the upset rear end 74 ofthe grounded contact rivet 41. The opening 72 is made large enough toprovide clearance around the upset portion 74.

In the manufacture of the switch, it is preferred to secure the contactrivet 41 to the tab 68 before the tab is bent or folded inwardly fromthe side wall 20 of the casing 12. In FIG. 6, the original position ofthe tab 6 8 is shown in full lines, while the inwardly folded positionis shown in broken lines. In its original position, the tab 68 projectsrearwardly from the side wall 20 of the casing. A score mark or groove76 is preferably formed between the side wall 20- and the tab 68 toinsure that the tab will be folded inwardly along the correct junctionline. The tab 68 is folded inwardly before the insulating plate 46 issecured to the rear side of the casing 12. To insure firm engagementbetween the insulating plate 46 and the tab 68, the tab may be foldedinwardly at an angle slightly less than 90 degrees, so that the tab willbe folded inwardly by an additional amount when the insulating plate ispressed against and secured to the rear side of the casing 12. Thus, theinsulating plate itself completes the inward folding movement of the tab68.

The switch may employ various arrangements of the contacts 41-44. In theillustrated arrangement, the contacts 42 and 43 are in one row, whilethe contacts 41 and 44 are in a parallel row. The contacts 42 and 43 arestaggered upwardly relative to the contacts 41 and 44.

When the contactor 14 is in its uppermost position, as shown in FIG. 2.,the contactor engages only the contact 42. This constitutes the Offposition of the switch. The contactor 14 may be moved downwardly to itsfirst operating position, in which the contactor engages the groundedcontact 41, in addition to the contact 42. An insulating point or boss78 may be provided on the insulating plate 46 to engage the contactor14, so as to provide three points of contact with the contactor. Theinsulating boss 78 is preferably in the form of a semiperforation,extruded or stamped forwardly from the insulating plate 46.

Further downward movement of the contactor 14 brings it to its nextoperating position, in which the contactor engages the contacts 41, 42and 43. When the contactor is moved downwardly to its lowermostposition, it engages the contacts 41, 43 and 44.

The switch may be employed in a variety of circuits to carry out variouscontrol functions. Such a circuit is shown by way of example in FIG. 2.The illustrated circuit is adapted to control the speed of a motor 80for a blower or other device. The motor 80 is connected between thecontact 44 and the ungrounded side of the battery 82. Of course, theother side of the battery is grounded, and thus is connected to thecontact 41, which is grounded through the casing 12. A resistor 84 isconnected between the contacts 43 and 44. Another resistor 86 isconnected between the contacts 42 and 43.

When the contactor 14 is in its uppermost position, the

motor is off, because the energizing circuit to the grounded contact 41is open. When the contactor 14 is moved downwardly so as to engage thegrounded contact 41, the energizing circuit for the motor 80 iscompleted through the resistors 84- and 86, so that the motor operatesat low speed. In its next position, the contactor engages the contact 43so as to short-circuit the resistor 86. Thus, the motor is energizedthrough the resistor 84, so that the motor operates at medium speed.

In the final or lowermost position of the contactor 14, it forms acircuit between the grounded contact 41 and the contact 44, so that themotor 80 is energized directly from the battery 82. Both of theresistors 84 and 86 are ineffective. Thus, the motor operates at maximumor high speed.

The contacts 41-44 are preferably made of copper or some other highlyconductive material. The use of such a material insures the maintenanceof low contact resistance between the contacts and the contactor 14,which also is normally made of copper or some other highly conductivematerial. Very little cost is involved in forming the grounded contact41 as a separate contact rivet or other member, mounted on the tab 68.

However, even this small element of cost may be eliminated in some casesby forming a contact point or boss 141 integrally with the tab or flange68, as shown in FIGS. 7-9. As in the case of the contacts 41-44, theintegral contact 141 is made with a generally spherical curvature. Thecasing 12 is normally made of sheet steel, with a zinc or cadmiumplating thereon. The plated steel is not as good as a contact materialas the copper of the rivet 41, but is good enough to meet therequirements of many situations. Thus, the integrally formed steelcontact 141 will give reliable service and adequately long life,provided the conditions of service are not too severe.

When the integrally formed steel contact 141 is employed, it ispreferred to arrange the switch so that the contactor 14 always engagesthe grounded contact 141, in all positions of the switch. FIG. 9illustrates such a modified contact arrangement, in which the contactor14 always engages the contact 141, and is movable into engagement with aseries of contacts 142-144, mounted on the insulating plate 46. Theother contact points 142-144 are preferably made of copper or some otherhighly conductive material. The tab or flange 68 is bent or foldedinwardly from the casing in the same manner as in the case of the switchof FIGS. 1-6.

It will be understood that the present invention provides a switchhaving at least one contact grounded directly to the casing of theswitch. In this way, there is no need to provide any wire or otherexternal connection to the grounded contact. The cost of the wire isthus avoided. The grounded contact is preferably mounted or formeddirectly on a tab or flange projecting inwardly from one wall of thecasing. Thus, the grounded contact may be provided at very low cost.Moreover, the electrical resistance between the contact and the groundedcasing is very low. The grounded contact is in the same plane as theother contacts and is rigidly supported against the insulating memberwhich supports the other contacts.

The present invention provides a switch which is extremely low in costyet will remain reliable in operation over an extremely long servicelife.

Various other modifications, alternative constructions and equivalentsmay be employed without departing from the true spirit and scope of theinvention, as exemplified in the foregoing description and defined inthe following claims.

I claim:

1. In an electrical switch,

the combination comprising a casing made of conductive material,

a contactor movable in said casing,

means for moving said contactor within said casing,

said means comprising an insulating carriage supporting said contactorand confined within said casing for movement along a predetermined paththerein,

an insulating member on said casing opposite said contactor,

at least one contact mounted on said insulating member and engageable bysaid contactor,

a conductive member formed integrally with said casing and adjacent theinner side of said insulating member within said casing,

and at least one contact on said conductive member and engageable bysaid contactor for connecting said contactor to ground through saidcasing.

2. A combination according to claim 1,

in which said casing is made of sheet metal,

and said member on said casing comprises a flange bent inwardly from onewall of said casing.

3. A combination according to claim 1,

in which said last mentioned contact comprises a contact rivet mountedon said member on said casing.

4. A combination according to claim 1,

in which said last mentioned contact comprises a contact point formedintegrally with said member on said casing.

5. A combination according to claim 3,

in which said insulating member is formed with an opening for receivingsaid contact rivet.

6. In an electrical switch,

the combination comprising a metal casing,

a carriage movable in said casing,

means for moving said carriage within said casing,

a contactor mounted on said carriage and movable therewith,

an insulating member mounted on said casing opposite said contactor andforming one wall of said casing,

at least a first contact mounted on said insulating memher andengageable by said contactor,

at least one tab formed integrally with one wall of said casing andprojecting into said casing adjacent the inner side of. said insulatingmember,

and at least a second contact on said tab and engageable by saidcontactor for connecting said contactor to ground through said casing.

7. A combination according to claim 6,

in which said second contact comprises a highly conductive contact pointmounted on said tab.

8. A combination according to claim 6,

in which said second contact comprises a conductive contact rivetmounted on said tab.

9. A combination according to claim 8,

in which said insulating member is formed with an opening for receivingsaid contact rivet.

10. A combination according to claim 6,

in which said second contact is in the form of a contact point formedintegrally with said tab.

References Cited by the Examiner UNITED STATES PATENTS 6/1954 Hubbell17457 X 9/1966 Schink 20016

1. IN AN ELECTRICAL SWITCH, THE COMBINATION COMPRISING A CASING MADE OFCONDUCTIVE MATERIAL, A CONTACTOR MOVABLE IN SAID CASING, MEANS FORMOVING SAID CONTACTOR WITHIN SAID CASING, SAID MEANS COMPRISING ANINSULATING CARRIAGE SUPPORTING SAID CONTACTOR AND CONFINED WITHIN SAIDCASING FOR MOVEMENT ALONG A PREDETERMINED PATH THEREIN, AN INSULATINGMEMBER ON SAID CASING OPPOSITE SAID CONTACTOR, AT LEAST ONE CONTACTMOUNTED ON SAID INSULATING MEMBER AND ENGAGEABLE BY SAID CONTACTOR, ACONDUCTIVE MEMBER FORMED INTEGRALLY WITH SAID CASING AND ADJACENT THEINNER SIDE OF SAID INSULATING MEMBER WITHIN SAID CASING, AND AT LEASTONE CONTACT ON SAID CONDUCTIVE MEMBER AND ENGAGEABLE BY SAID CONTACTORFOR CONNECTING SAID CONTACTOR TO GROUND THROUGH SAID CASING.